Clinical and immunological assessment of thyroid pathology in rheumatoid arthritis.

Introduction: Rheumatoid arthritis (RA) is a chronic systemic autoimmune disease characterized by joint inflammation and significant extra-articular comorbidities. The autoimmune thyroid disease (AITD) is among the most frequent endocrine disorders associated with RA, reflecting potential shared immunopathogenic mechanisms. Aim: To evaluate the prevalence and clinical characteristics of thyroid dysfunction and autoimmunity in female patients with RA in comparison with a matched cohort of healthy controls and assess their association with disease activity and anti-cyclic citrullinated peptide antibodies (ACPA) positivity. Materials and methods: A cohort of 139 female RA patients was compared to 97 healthy controls. Thyroid function (TSH, fT4) and thyroid-specific antibodies (TPOAb, TgAb) were measured. RA disease activity was assessed using DAS28-ESR, with statistical analyses examining associations between thyroid pathology and RA features. Results: The prevalence of thyroid dysfunction among RA patients was 40.2%, which was significantly higher than the 8.24% observed in controls (p<0.001). Clinical hypothyroidism occurred more frequently in the RA group (20.86%). RA patients also had higher rates of TPOAb and TgAb positivity (37.28% and 30.5%, respectively) compared to controls. ACPA and TPOAb levels demonstrated a strong positive correlation (r=0.6375). Moreover, higher RA disease activity correlated with an increased prevalence of thyroid pathology. Conclusion: Thyroid dysfunction and autoantibody positivity are significantly more prevalent in RA patients, suggesting shared autoimmune mechanisms. Routine thyroid function and antibody screening in RA management may facilitate early detection and improve outcomes.